The present invention relates to security enhancement for distribution of electronic documents and more particularly to techniques for "fingerprinting" electronic documents to identify a particular authorized recipient.
With the development of the Internet and other electronic networks, it has become desirable to distribute text documents electronically. Electronic distribution of text documents is both faster and cheaper than distribution of paper copies. However, if controlled distribution is desired the low cost and instantaneousness of electronic distribution in combination with the ease of copying electronic documents give rise to a serious security problem. Once an electronic document is transmitted to one party, it may be easily copied and distributed to others without authorization by the owner of rights in the electronic document or often without even his or her knowledge. This type of illicit document distribution may deprive the owner of income or may lead to unauthorized disclosure of otherwise confidential information.
It is known to particularize paper documents to identify an authorized recipient by slight variation in the appearance of fonts. By close analysis of font appearance, one can determine the source of an unauthorized copy. This technique is however largely useless in the context of electronic document distribution where it is typical to transmit only text without font appearance information.
What is needed is a system for enhancing the security of electronic document distribution.